This invention relates to systems for transferring fingerprints and, more particularly, to such systems which utilize an image transfer medium which does not stain the subject's finger with a colored ink.
The art of "taking" fingerprints and comparing the images so obtained with pre-recorded ones to establish the identity of the person fingerprinted is old.
The procedure normally used requires that the subject's finger be first pressed against a smooth plate, usually of glass, on which a thin layer of ink has been deposited with the aid of a brayer, and then rolled against a piece of paper or other ink-printable medium. The process is time consumming and messy, and requires considerable skill on the part of the practitioner, especially in the techniques of spreading the ink on the plate, applying the finger to the inked surface, and transferring the print to the receiving surface. For these reasons the practice is generally restricted to the criminal investigation, security and administrative identification fields.
Modern commerce, with its increasing reliance on negotiable documents such as checks, bank drafts and the like, and on credit transactions using credit cards, for its smooth operation is in great need of a simple and foolproof method of establishing the identity of individuals presenting themselves as the rightful owners of such documents and demanding that they be honored without delay. The best method of proving, or disapproving, identity in the event of a subsequent dispute as to the right of the claimant to the funds, goods or services supplied, would be to retain a clear fingerprint of the individual, a thumbprint for example, as part of the receipt, endorsement, or other memorandum of the transaction.
That such an identification system is not in common use can be directly attributed to the inconvenience of prior art methods of securing fingerprints. Customers, rightly, object to ink-smeared fingers, time delays, and other disturbing aspects of these methods.
Many proposals to simplify the procedures or to avoid the problems complained of have been made. These range from methods employing the natural secretions of the skin to produce a latent image which can be developed with chemical reagents sensitive to the amino acids or other constitutents transferred to a receiving surface, to complex automated electro-optical devices which reproduce "live" prints photographically. Most such proposals contain features which are as undesirable, for successful commercial use, as those involved in the conventional fingerprinting process. Consequently, none of these has achieved any considerable success in the marketplace.
It is the primary object of the subject invention to teach a simple, convenient, economical process for permanently recording fingerprints.
It is a further object of the invention to teach the use of non-staining chemical compositions, and developers for them, which permit the formation of highly visible sharply defined fingerprint images on a variety of substrates.
It is another object of the invention to teach the construction, method of production, and use of hard-surfaced nonsmearing pads for the storage and application of such non-staining chemical compositions.
It is yet another object of the invention to teach the construction and use of a compact self-contained portable kit with which the aforementioned process may be performed anywhere by minimally trained personnel.
The subject invention attains these and other objects by providing a hard-surfaced pad with controlled internal porosity and impregnated with a soluble metallic salt, preferably anhydrous ferric chloride, dispersed in a glycerine carrier medium. Applying the distal surface of the subject's finger against the unyielding surface of the pad transfers a thin, uniform layer of the metallic salt to the ridges of the skin. The salt is deposited on a suitable substrate by pressing the finger against it with a rolling motion.
A developer in the form of an organic base, preferably 8-hydroxyquinoline dissolved in acetone, is applied to the latent print on the substrate as a fine spray from an aerosol container. The metallic salt and the organic base form a colored chelate and render the fingerprint visible and permanent.
In kit form the invention comprises a box with a hinged cover and an inset top. A resilient metal plate attached to the underside of the cover is adapted to receive and hold a document or instrument to be identified with the subject's fingerprint. An opening in this plate is in registry with a similar opening in the top. The aforementioned pad, impregnated with the fingerprinting medium, is recessed in the top of the box.
An aerosol container, charged with developer, is securely mounted in the box below the top, with its spray orifice directed to discharge a metered quantity of spray against that portion of the document exposed through the openings in the cover and the top, when the cover is closed against the box. A finger-operated, spring-biased lever arm is mounted through one side of the box to allow the operator to actuate the aerosol valve.
In operation, the document or instrument is placed under the resilient plate and aligned to expose the intended location of the fingerprint in the opening. The subject's finger is rolled lightly over the pad and then applied to the exposed surface of the document. A handle mounted on the outside of the cover supports it during this process.
The cover is then closed and the valve-lever actuated, thereby discharging a metered quantity of developer against the invisible image on the document, rendering it visible and permanent and providing positive identification of the subject on the document or instrument.